Arc-extinguisher



F. E. RICKETTS.

ARC EXHNGUiSHER.

APPLICATION FILED MAR. 1:. 1916.

INVENTOR Forrest E. Rickezfs.

AITTORNEY FORREST E. RICKETTS, 0F BALTIMORE, MARYLAND.

ARG-E'XTINGUISHER.

Specification of Letters Patent.

Patented July 1, 1919.

Application filed March 13, 1916. Serial No. 83,786.

To all whom it may concern:

. Be it known that I, Fonnns'r E. RIcKE'rTs, a citizen of the UnitedStates, and a resident of Baltimore, in the State of Maryland, haveinvented a new and useful Improvement in Arc-Extin uishers, of which thefollowing is a specification.

My invention relates to electrical systems of distribution andparticularly to apparatus for extinguishing arcs that occur in suchsystems without disturbing the operation of the apparatus connectedthereto.

One object of my invention is to provide a device of the above indicatedcharacter that shall so alternately open and close a circuit interrupterto reduce the voltage of the circuit that the arc will be extinguishedwithout causing the apparatus connected to the circuit to fall out ofsynchronism.

Another object of my invention is to provide a device of the aboveindicated character that shall have means for preventing the automaticopening and closing of the interrupter if the arc is not extinguishedWithin a predetermined time.

My 'copending application, Serial No. 735,376, filed December 7, 1912,discloses a device for reducing and restoring the voltage of a generatorto extinguish an arc. The device operates upon the principle that an arcwill break within a fraction of a second after the voltage has beenreduced substantially to zero. While a device of this type operatessatisfactorily in a distributing system as a whole, it does not providemeans for independently extinguishing the arcs in the feeder circuits.In my present invention, I provide a circuit interrupter that is adaptedto be opened when a short circuit or an arc occurs, and I furtherprovide means for reelosing the interrupter in accordance with thedifference in voltage between the respective sides of the interrupter.Since some short circuits are of a permanent nature and are notmaintained by an are, I provide means to prevent the continued automatico ening and closing of the interrupter if the short circuit persists fora predetermined time. It has been found that this time should be suchthat an ordinary are would be extinguished if the interrupter werepermitted to alternately open and close a predetermined number of times.

The single figure of the accompanying drawing is a diagrammatic view ofa distributing system that -is provided with an arc-extinguishing meansembodying my invention.

A generator 1 supplies energy to the main conductors 2, 3 and 4 of adistributing system 5. A feeder circuit 6, comprising conductors 7, 8and 9, is operativcly connected between the main distributing circuit 5and a load 10, such as a motor or other similar device. The feedercircuit 6 is provided with a circuit. interrupter 11 and with seriestransformers 12, 13 and 11 that are connected to its respectiveconductors.

The circuit interrupter 11 is provided with a. closing elcctromagnet 15and a tripping clcctromagnet 16. The secondary windings of thetransformers 12, 13 and 14 are operatively connected to windings 17 and18 of overload relays 19 and 20 that are provided with movable contactmembers 21 and 22. The movable contact members 21 and 22 are adapted toengage stationary contact members 23 and 24 when a short circuit occurson the feeder circuit 6. The contact members 23 and 24 are connected inparallel between one terminal of the winding of the electromagnet 16 andone terminal 25 of an electromotive force generator 26. The otherterminal of the electromagnet 16 is connected to the other terminal 27of the electromotive force generator 26. Thus, the circuit breaker 11 isadapted to be tripped when a short circuit occurs across any of theconductors of the feeder circuit 6.

The primary winding of a transformer 28 is connected across theconductors 3 and 4 of the main circuit 5, and the primary winding of asimilar transformer 29 is connected across the corresponding conductors7 and 8 of the feeder circuit 6. Thus, the primary windings of thetransformers 28 and 29 are, in reality, connected to the same conductorsbut are separated by the circuit interrupter 11. The secondary windingsof the transformers 28 and 29 are so connected to two conductors 30 and31 that, when the circuit interrupter 11 is closed, one of the windingsneutralizes the effect of the other, and no current traverses theconductors 30 and 31. However, when the circuit interrupter 11 istripped, the voltage of the transformer 29 Wlll be substantially zerowhile the voltage of the transformer 28 will be substantially normal.Hence, voltage proportional to the normal voltage of the circuit will beimpressed across the conductors 30 and31.

The conductor 30 is connected to one sta tionary contact terminal 32 ofa doubleole single-throw switch The correspon ing st: tionary contactterminal 34 of the switch 33 is connected, through a conductor 35, toone terminal of the winding of the electromagnet 15 the other terminalof which is connected to the terminal 27 of the generator 26. Theconductor 35 is also connected to the stationary contact terminal 36 ofa singlepole double-throw switch 37 the other stationary contactterminal 38 of which is connected, through a conductor 39, to oneterminal of the winding of the electromagnet 16. The movable contactmember 40 of the switch 37 is connected to the terminal 25 of thegenerator 26. The movable contact member 41 of the switch 33 isconnected to a stationary contact member 42 of a relay 43. and theremaining movable contact member 44 of the switch 33 is connected,through a conductor 45, to one terminal of the winding 46 of a relay 47and to one terminal of the winding 48 of a definite timelimit relay 49.The conductor 31 is con HELlBd to the other terminal of the winding 46and also to the other terminal of the winding 48 of the relay 49. Theother stationary contact member 50 of the relay 43 is connected to theterminal 25 of the source 26. One terminal of the winding 51 of therelay 43 is connected to the stationary contact member 50, and the otherterminal of the winding 51 is connected to the stationary contact member52 of the relay 47. The other stationary contact member 53 of the relay47 is connected, through a conductor 54, to the terminal 27 of thegenerator 26. The winding 51 of the relay 43 is adapted to actuate amovable bridging contact member 55 to engage the stationary contactmembers 42 and 50, and the winding 46 of the relay 47 is adapted toactuate a movable bridging contact member 56 to engage the stationarycontact members 52 and 53.

The relay 49 may be constructed as set forth in application, Serial N 0.771,888, filed by A. W. Copley and B. H. Smith and assigned to theWestinghouse Electric and Manufacturing Company, and comprises a mainwinding 48, an auxiliary winding 57 and secondary windings 58. Anormally saturated transformer 59 is operatively connected between thewindings 57 and 58 in order to cause the armature 60 to rotate at aconstant speed irrespective of the energy traversing t e winding 48. Thearmature 60 is mounted on a shaft 61 u on which a movable contact member62 is a so mounted. The movable contact member 62 is adapted to en age astationary contact member 63 a pre etermined time after the winding 48is energized. The contact members 62 and 63 constitute the separableterminals of a winding 64 that is ada ted to so cooperate with themovable mem er of the relay 47 that, when the winding 64 is shortcircuited, the movable contact member 56 will not engage the stationarycontact members 52 and 53.

When a short circuit, such as an arc, occurs on the feeder circuit (3,sufficient energy will traverse the windings of the transformers 12, 13and 14 to cause the movable contact members 21 and 22 of the relays 19and 20 to engage their respective stationary contact members 23 and 24to complete a circuit from one terminal of the generator 26 through theelectromagnet 16 to cause the circuit interrupter 11 to be tripped.\Vhen the circuit interrupter 11 is tripped, sufii cient voltage will beimpressed across the conductors 30 and 31 to cause the rela 47 tooperate. The operation of the relay 47 will efi ect engagement betweenits movable contact member 56 and its stationary contact members 52 and53, and the relay 43 will operate to effect engagement between its stationary contact members 42 and 50 and its movable contact member 55.\Vhen the movable contact member 55 engages the stationary contactmembers 42 and 50, a circuit will be completed from one terminal of thegenerator 26 through the stationary contact member 34 and the movablecontact member 41 of the switch 33, the conductor 35 and theelectromagnet 15 to the other terminal of the generator 26. Thus, theelectromagnet 15 will be energized to close the circuit interrupter 11.Since the time between the opening and closing of the circuit interrupter 11 is relatively short, the motor 10 will not drop out ofsynchronism, but any are across the conductors of the feeder circuit 6will be extinguished. However, if the arc persists after the circuitinterrupter 11 is closed, the relays 19 and 20 will again operate to soenergize the electromagne-t, 16 as to trip the circuit interrupter 11,and, when the interrupter 11 is again tripped, the transformers 28 and29 will again effect the operation of the relays 47 and 43 toimmediately close it.

It has been determined that, if the short circuit is caused by anon-permanent are, it will be extinguished by reducing the voltage tosubstantially zero a: number of t mes. However, if the short circuit ispermanent in nature, it is advisable to prevent the automatic alternateopening and closing of the circuit interrupter after the,expiratio n ofa time period during which the circuit interrupter has opened and closeda predetermined number of'times. Thus, the first time that the circuitinterrupter 11 is interrupted, the winding 48 of the relay 49 will beenergized and its armature 60 will start to operate, and, after apredetermined time interval, the contact member 62 will engage 130 thecontact member 63 to short circuit the winding 64 of the relay 47 andthus render the relay 47 inoperative. Consequently, the circuitinterrupter 11 will remain open so long as the Winding 6st of the relayH remains short circuited. The relay 4? will thus remain inoperativeuntil the voltage across the winding 4-8 or the Winding 46 has beenreduced to zero for a sufficient time period to return the mo 'ablecontact member 56 to its original position. This may be accomplishedafter the trouble on the feeder circuit (3 has been cleared by openingthe switch 33 and closing the circuit interrupter I] by moving themovable contact member d0 of the switch t? into engagement with itsstationary contact terminal 56. Thus, the motor 10 may be disconnectedfrom the ma n circuit 5 when permanent short circuit (r-curs thereon,and when this short circuit hos been removed and the circuit interrupterii is again closed, the arc-extinguish cv ce in such a position that itmay a,! in operate immediately hiil'nilarly, it the are should beextinguished before the contact llltli'llltl SE2 engages the stationarycontact member 133 of the relay 49, the circuit intcrru 'iter ii wiil beclosed, the motor it will continue to operate and the relays will be insuch position as to be operative whenever another short circuit occurs.

I do i iiniit my invent ion to the particuces shown, as manymodifications may he made therein without departing from the spirit and,scope of my invention as set torth in the appended claims.

I claim as my invention:

1, In system of distribution, the coin hination with a. circuitinterrupter and means for opening it when an arc obtains on the system,of a relay so connected to the circuit that, when a difference inpotential obtains across the interrupter, it will cause the interrupterto be reclosed, and means for so controlling the operation of said relaythat the interrupter will be precluded from reclosing after the arc haspersisted for a predetermined period of time.

2. In a system. of distribution, the combination with a circuitinterrupter and means for opening it when an arc obtains on the system,of a relay so connected across the interrupter that, when a. differencein potential obtains thereacross, the interrupter will be reclosed, andmeans for so controlling the operation of said relay that the interruptewill be precluded from reclosing when the are persists for apredetermined period of time.

3. In a system of distribution, the combination with a circuitinterrupter and means for opening it when an arc obtains on the system,of a relay so connected across the interrupter that, when a diflerencein potential obtains thereacross, the interrupter will be reclosed, anda time-element device for so controlling the operation of the relay thatthe interrupter will be precluded from reclosing when the arc persistsfor a predetermined period of time.

4. In a system of distribution, the combination with a circuitinterrupter, of means for tripping the circuit interrupter when an arcobtains on the system, and means dependent upon the difference involtage between the terminals of the circuit interrupter forautomatically closing the same.

5. In a system of distribution, the combination with means fordisconnecting a portion of the system when an arc obtains thereon, ofmeans dependent upon a (litterence in voltage between the two portionsof the system for reconnecting the same.

6. In a system. of distribution. the combination with means forautomatically re ducing the voltage of the system and for restoring itsvoltage before the apparatus connected thereto falls out ofsynchrrimisni, of a timedimit relay for preventing the restoration ofthe voltage utter it has been alternately reduced and restored for apredetermined time period.

7. In a system of distrilnition, the cone hination with means forautoimitimlly disconnecting a portion of the system when an arc obtainsthereon and for reconnecting the same before the apparatus connectedthereto falls out of synchronism, of means for preventing thereconnection after the arc has existed a predetermined time period.

8. In an alternating-currcnt system of distribution, the eon'ibinationwith a feeder circuit and a circuit interrupter therefor, of means fortripping the interrupter when an arc obtains on the feeder circuit,means dependent upon the difi'erence in voltage between the terminals ofthe interrupter for closing it, and a relay adapted to render thereclosing means inoperative predetermined time period after the areobtains.

9. In a system of distribution, the combination with a circuitinterrupter and means for opening it when an arc obtains on the system,of a relay for reelosing the interrupter, transformers so connected toboth terminals of the interrupter that, when it is tripped, sufiicientenergy will be supplied to the relay to reclose the interrupter, and atime-limit relay adapted to prevent the reclosure of the circuitinterrupter when the arc persists for a predetermined time period.

'10. In a system of distribution, the combination with a circuitinterrupter and means fo tripping it When an arc obtains on the system,of a relay for reclosing the interrupter. transformers so connected tothe terminals of the interrupter that, when it is tripped, sufiicicntenergy will be supplied to the relay to reclose the interrupter,

a definite time-limit relay adapted to pre' vent the automatic reclosureof the circuit interrupter when the arc persists for a predeterminedtime period, and means for normally reclosing the circuit interrupter.

11. In a system of distribution, the combination with a circuitinterrupter, of means for tripping the interrupter when an arc obtains0n the system, automatic means dependent upon a difference in voltageacross the interrupter for reclosing the interrupter, and means forpreventing the reclosure of the interrupter when the arc persists for apre-determined period of time.

12. In a system of distribution, the combination with a circuitinterrupter and means for opening it when an arc obtains on the system,of means for reclosing the interrupter, means so connected to theterminals of the interrupter that, when it is opened, sufiicient energywill be supplied to the reclosing means to reclose the interrupter, anda definite time-limit relay for so controlling the reclosing means thatthe interrupter is prevented from reclosing When the are persists for apredetermined period of time.

In testimony whereof, I have hereunto subscribed my name this 8th day ofMarch 1916.

FORREST E. RICKETT S.

